Asphalt paving screeds typically require auxiliary heaters, or burners, to apply heat to the material contacting plate of the screed to prevent sticking of asphalt paving material to the screed plate. U.S. Pat. No. 3,557,672, issued Jan. 26, 1971 to Albert L. Shurtz, describes a burner system and baffle arrangement to direct a flow of heat from a plurality of burners to selected surfaces of the screed assembly. An alternative arrangement in which the screed of an asphalt paver is heated by oil maintained in a reservoir that is in heat-transferring contact with the screed plate is described in U.S. Pat. No. 5,096,331 issued Mar. 17, 1992 to Larry Raymond. The burners or other heating arrangements of presently known screed systems typically require hydraulic or fuel systems, controls, and electrical systems to heat the material contacting plates. Such systems are costly to construct and troublesome to maintain.
The present invention is directed to overcoming the problems set forth above. It is desirable to have a screed assembly that does not require any form of auxiliary heating to prevent freezing, or sticking, of the paving material to the screed plate. It is also desirable to have a screed plate that is economical to produce and maintain.
The present invention overcomes the above described problems by providing a material contacting member, or screed plate, that has low heat transfer properties, i.e., low thermal conductance, and limited heat energy storage capacity. As a result of these characteristics, the screed plate embodying the present invention is capable of being heated at a desirable rate and maintained at a temperature sufficient to prevent sticking of the asphalt material to the plate, solely by heat transferred from the paving material. Furthermore, the present invention effectively eliminates the large thermal gradient that, heretofore, was inherently present between the plate and paving material.